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参照OSL测年和考古与历史学断代,利用黄土—土壤剖面沉积物中炭屑和黑碳(焦炭和烟炱)记录,结合磁化率、有机碳等古环境指标,揭示过去12000年火灾历史演变过程。炭屑和黑碳浓度研究结果表明:全新世早期区域野火活动频繁发生,中期火灾很少,晚期本地火灾频率呈现增长态势。黑碳(烟炱和焦炭)和炭屑分析呈现不平行变化趋势,可能是生物质燃烧的物质排放方式和传输过程的区域差异引起。距今3500~2800年间,黑碳和炭屑颗粒浓度峰值与全新世短尺度恶化气候事件具有明显同步性;同期,先周人部落大规模土地开垦发展旱作农业活动加剧。黄土高原千年尺度火灾变化与季风气候变化之间的关系表明:全新世以来,野火频率变化取决于区域气候有效湿度和人类土地利用及其对气候变化的响应。
According to the OSL dating and archeological and historical records, the history of fires in the past 12,000 years was revealed based on the records of carbon sequestration and black carbon (coke and soot) in the loess-soil profile sediments and the paleoenvironmental indicators such as magnetic susceptibility and organic carbon process. The results of carbon black and black carbon concentrations show that wildfires occurred frequently in the early Holocene, with few fires in the middle period and the local fire frequency in the late stage showed an increasing trend. The analysis of black carbon (soot and coke) and charcoal showed a non-parallel trend, which might be caused by the regional differences in the emission patterns and transport processes of biomass combustion. From 3500 to 2800 years ago, the peaks of black carbon and carbonaceous particulates concentration were obviously synchronized with the short-range deterioration events of the Holocene. In the same period, the activities of large-scale arid land reclamation and development of dry-farming agriculture intensified. The relationship between the monsoon climate change and the change of the monsoon climate over the Loess Plateau shows that the change of the wildfires frequency depends on the regional effective humidity and human land use and its response to climate change since Holocene.